A fluid energy machine, in which pistons perform an oscillating axial movement in cylinders, is described as piston machine in engineering. The transmission of the mechanical work in piston machines of this type is typically performed by means of special pushrods, so-called connecting rods, which convert the linear movement of the piston into the rotary movement of a so-called crankshaft. Common materials for connecting rods according to the prior art comprise, in addition to the traditionally used cast iron, mainly micro-alloyed steels and sintered metals. For individual applications, for example in the sports engine sector, special heat-treatable steels or the particularly light titanium are alternatively employed.
So-called cracked connecting rods enjoy widespread distribution. Such a connecting rod is initially produced in one piece, then—depending on the base material used—provided with a fracture or laser notch and finally specifically broken into two parts. Both parts are screwed together during the connecting rod assembly and unambiguously fit together along their mutual fracture surfaces. The construction of connecting rods split in such a manner is explained by Greuter/Zima/Hoffmann in “Motorschäden”, Vogel Buchverlag, ISBN 3-8343-3056-6, pages 203 f.
A laser-notched connecting rod is known for example from DE 10 2004 026 297 A1. On the connecting rod described there a bearing is provided, which has a splitting surface running through the bearing, which is formed by fracture-splitting the bearing, wherein the bearing in sections is provided with a splitting notch, which over its overall length consists of variations with respect to its angular orientation regarding the partition plane, wherein the notching sections corresponding to these versions run parallel to a section line of the splitting plane with the bearing surface.
Problematic in this case proves to be the exact reproducible positioning of the severed so-called connecting rod cap as part of the connecting rod assembly. In addition, the lateral forces that act on the connecting rod during the operation of the crank drive have to be transmitted. With respect to this setting of problems, the use of pins running perpendicularly to the connecting rod joint for the additional axial stabilisation of cracked or otherwise split connecting rods is known from the prior art.